We'll defend Manus to the hilt: PNG

Papua New Guinea's government will "defend to the hilt" a legal challenge being brought against the Australian-run detention centre on Manus Island.

Lawyers acting on behalf of PNG Opposition Leader Belden Namah are seeking to have the Manus facility declared unconstitutional and will ask the court to temporarily stop asylum seeker transfers until it has made its final decision.

But Attorney-General Kerenga Kua says the government has not been served with any court documents notifying them of the challenge in the Court of Human Rights on Tuesday morning.

"We are informally aware of its existence and of the need for tomorrow's scheduled mention in court. Somebody will be attending as a friend of the court to find out what's going on," Mr Kua said.

"If we haven't been served, nothing can happen, it can't be heard and we want to be heard ... we will defend this to the hilt."

Loani Henaos, of Henaos Lawyers, who is bringing the challenge on behalf of the opposition, says the government was served with the documents on February 2.

"The government's lawyers have acknowledged that," he said.

"They have filed a notice of an intention to defend."

There are 274 detainees at the temporary Manus facility - including more than 30 children - living in conditions that have been widely criticised as inhumane.

Mr Kua has argued the site is legal under the nation's immigration law, which grants power to the immigration minister to set up a processing facility.

Mr Henaos says that's unconstitutional.

"The memorandum of understanding between Australia and PNG is unconstitutional on the basis that it allows the PNG government to bring in asylum seekers from a foreign country, and the minute they put their foot on PNG territory, they are arrested," he said.

"We're saying every person - whether you're a national, PNG citizen or a foreigner - when you come into the country you have your personal liberty guaranteed under the constitution.

"They were made to come in and then were arrested."

Mr Kua has in the past rejected the definition of the site as a detention centre.

"We are providing them with a place to live," he told AAP in January.

"It's not a detention centre, as people call it.

"There is no law in our country that authorises us to establish a detention centre. But under our migration act, the minister can set up a processing facility."

The United Nations High Commissioner for Refugees recently labelled the centre unlawful.

The agency released a damning report on February 4 slamming conditions at the facility - which mostly comprises tents - and called for the transfer of children there to be suspended.

It said the situation was at odds with Australia's international obligations, and children should not be transferred there until all appropriate legal and administrative safeguards were in place.

Australian Greens senator Sarah Hanson-Young, who visited the site in late January, said children were witnessing self-harm and suicide attempts by adults.

The Australian government announced a deal with New Zealand on Saturday to send 150 refugees a year across the Tasman from centres such as Manus and the one on Nauru.

The court hearing is expected to start at 1030 (AEDT) on Tuesday before Justice David Canning in Port Moresby.

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